This application relates to a brake for a hydraulic device. It is particularly applicable to a hydraulic device of the type in which an eccentrically mounted shaft is adapted for orbital and rotational motion. Even more particularly, the present invention is useful as a motor brake in a hydraulic motor in which the orbital and rotational movement of the shaft is effected by the cooperating action of a gerotor gearset.
Hydraulic motors are designed to use high pressure fluid, to drive a mechanical output shaft. A particularly advantageous form of a hydraulic motor has been found to be one in which a series of expanding and contracting pockets are formed by relative rotational and orbital movement of a pair of gear members conventionally known as a gerotor gearset.
One of the gears of the gearset is generally supported by an eccentrically mounted shaft. In such motors an output shaft coupled to the eccentrically mounted shaft is rotated due to the torque applied to the eccentrically mounted shaft by the high pressure input fluid causing expanding and contracting of the fluid pockets formed by the gerotor gearset. In order to properly time the delivery of high pressure fluid to the pockets, and to convey low pressure fluid from the pockets, there is provided a commutation valve arrangement.
Such types of hydraulic devices require means for applying a braking force to the rotating driven shaft. There has been a need in the art for inexpensive, high torque braking systems which can be applied to hydraulic motors, and which can be actuated automatically when input fluid pressure falls below a predetermined minimum.